Build Your Own Faraday Cage. Here’s How.

by M.D. Creekmore on July 29, 2013 · 53 comments

This is a guest post written for TheSurvivalistBlog.net by Arthur Bradley – Author of “Disaster Preparedness for EMP Attacks and Solar Storms“.

Introduction to Faraday Cages

There is a great deal of confusion about Faraday cages. Not only about how to build them, but also what they actually protect against. In this article, Dr. Arthur Bradley, author of Disaster Preparedness for EMP Attacks and Solar Storms, answers a few basic questions and perhaps debunks a few myths.

What is a Faraday Cage?

A Faraday cage (a.k.a. Faraday shield) is a sealed enclosure that has an electrically conductive outer layer. It can be in the shape of a box, cylinder, sphere, or any other closed shape. The enclosure itself can be conductive, or it can be made of a non-conductive material (such as cardboard or wood) and then wrapped in a conductive material (such as aluminum foil).

Faraday Cage box

What does it do?

A Faraday cage works by three mechanisms: (1) the conductive layer reflects incoming fields, (2) the conductor absorbs incoming energy, and (3) the cage acts to create opposing fields. All of these work to safeguard the contents from excessive field levels. A Faraday cage is particularly useful for protecting against an electromagnetic pulse that may be the result of a high-altitude nuclear detonation in the atmosphere (a.k.a. EMP attacks). Despite rumors to the contrary, a Faraday cage is not necessary to protect against solar coronal mass ejections because the frequency content of such disturbances is at much lower frequencies—they don’t couple energy efficiently into small-scale electronics, except through conducted paths (e.g., wires coming into the system). A better precaution against solar events is to unplug electronics and use quality surge suppressors.

How does field cancelation work?

Field cancelation occurs when the free carriers in the conductive material rapidly realign to oppose the incident electric field. If the cage is made from something non-conductive, the free carriers are not mobile enough to realign and cancel the incident field.

How thick should the conducting layer be?

The conductive layer can be very thin because of something known as the skin effect. That term describes the tendency of current to flow primarily on the skin of a conductor. As long as the conducting layer is greater than the skin depth, it will provide excellent shielding because the absorption loss will be large. The skin depth is a function of the frequency of the wave and the conductor material. As an example, consider that for a frequency of 200 MHz, the skin depth of aluminum is only about 21 microns. EMP pulses can have frequency content that ranges up to 1,000 MHz. Therefore, wrapping a box in a couple of layers of heavy duty aluminum foil (typically about 24 microns thick) provides the necessary conductor thickness to protect against high-frequency radiated fields.

Does it matter what type of conductor is used?

Not much. The conductivity of nearly any metal is good enough to allow the carriers to easily realign to cancel external fields. For example, if silver (the best conductor) is used in place of aluminum, the skin depth at 200 MHz is reduced to about 4.5 microns. Of course, the high cost of silver would prevent using it for such a purpose.

Can a Faraday cage have holes?

Yes, as long as the holes are small with respect to the wavelength of the incident electromagnetic wave. For example, a 1 GHz wave has a wavelength of 0.3 meters in free space. As long as the holes are significantly smaller than that dimension (i.e., a few millimeters), they won’t let in much of the incident wave. This is why fine conductive mesh can be used when constructing a Faraday cage. In practice, the cage’s lid or door usually causes the most leakage. Taping the seam with conductive tape helps to reduce this leakage.

Can you use existing conductive enclosures?

Yes, there are many conductive enclosures that can be used, including ammo cans, metal garbage cans, anti-static bags, and even old microwave ovens. Each has its own level of effectiveness as covered in my book, Disaster Preparedness for EMP Attacks and Solar Storms. The key criterion is that the gaps and seams remain very small.

Must the cage be grounded?

There is a great deal of confusion regarding grounding of a Faraday cage. Grounding of the cage (i.e., connecting it to some Earth-referenced source of charge) has little effect on the field levels seen inside the box. Grounding primarily helps to keep the cage from becoming charged and perhaps re-radiating. The bottom line is that an ungrounded cage protects the contents from harmful electromagnetic fields as well as a grounded one.

Anti-static Bags

Anti-static bags are readily available to protect electronic components against electrostatic discharge. They can be purchased in many different sizes, including some large enough to hold radio equipment. While they do offer shielding from EMP, not all products are created equal. Testing confirmed that products certified to MIL-PRF-8170 and/or MIL-PRF-131 offer the greatest protection from an EMP. The results from testing three different types of bags are provided in Disaster Preparedness for EMP Attacks and Solar Storms. When selecting an ESD bag, consider not only the shielding effectiveness but also the physical ruggedness of the bag. A tear or large hole can compromise the bag by allowing EMP energy to enter.

Static Bags

Larger Faraday Cages

Storing a larger set of electronics might require an entire room. Engineers who work in electromagnetics often use “shield rooms” to conduct experiments because they do an excellent job of filtering out interfering signals, providing in excess of 100 dB of shielding. A poor-man’s shield room can be made by lining a small closet with heavy-duty aluminum foil, covering all four walls, the floor, the ceiling, and the inside of the door. Overlap and tape the seams using either conductive or regular cellophane tape. There can be no conductive penetrations into the room, or it will seriously degrade the shielding. Cover all electrical outlets, light switches, etc. with aluminum foil. Do not plug anything into the electrical outlets. Also, lay a piece of plywood or cardboard on the floor so that it can be walked on without damaging the aluminum foil. Rooms built in this way have been shown to offer more than 50 dB of shielding up to several hundred MHz.

Faraday Room

For More Information

For more information about Dr. Bradley’s books, see http://disasterpreparer.com . To sign up for his free Practical Prepper Newsletter, Email: newsletter@disasterpreparer.com .

53 comments

lilbear68 July 29, 2013 at 10:18 am

youre making faraday cages a complicated mess when for much stuff its very simple. a steel trash can with a tight fitting lid. is all thats needed. just make sure there is no conductive contact to the contents

Arthur Bradley August 7, 2013 at 10:16 am

You’re mostly right. A steel trash can with a very tight fitting lid does a pretty good job of acting as a Faraday cage. I tested this as part of my book, and found that it varies greatly depending on the fit of the lid. One addition that helps is to tape the seam of the trash can with conductive tape.

Stay safe,

Arthur

Jon July 29, 2013 at 11:54 am

Does anyone know if you can use packing peanuts to insulate and keep the contents of the cage from contact with the exterior walls?

Mama J July 29, 2013 at 12:12 pm

I was told by other pack members that styrofoam makes static electricity.
Now, the corn starch ones might work. I use chunks of rubber.

Arthur Bradley August 7, 2013 at 10:19 am

Styrofoam is an insulator that would work fine in a Faraday cage. The static issue is a concern when two objects are moving with respect to one another (i.e., see the Triboelectric effect). It would be fine sitting inside a Faraday cage as long as you’re not scrubbing your bare electronics against it.

Stay safe,
Arthur

Alan July 29, 2013 at 12:39 pm

Question about gaps: If I use an ammo can with a rubber gasket to make the ammo can (and radio equipment) waterproof, having to repeatedly re-seal the can with conductive tape seems like a real pain. How do I calculate the maximum allowable gap? My first-order thought/guess is that it is related to the frequency spectrum expected in an EMP event.

Mike July 29, 2013 at 1:37 pm

Try lining the lip and lid with steel wool to keep the seal between lid and container.

Arthur Bradley August 7, 2013 at 10:21 am

Try to keep the gap smaller than 1 mm (about the thickness of a dime). I tested ammo cans for my book, and they didn’t do great because of the less than perfect seam going around them.

Arthur

patientmomma July 29, 2013 at 4:11 pm

I read on another blog that an old microwave oven (old plugged of course) could be used for small items. Does anyone know if this is true?

OhioPrepper July 29, 2013 at 8:58 pm

patientmomma,
Yes it’s true, and was stated as such in the article.

Thomas T. Tinker July 29, 2013 at 4:26 pm

I went for the steel trash can with blanket foam wrap on the inside and a heavy steel wool ‘gasket’ on the lid. 4 harbor freight coffin locks on the lid and a ground server bolt with a leg of jumper cable. I left the clamp on one end to make it ‘portable’. It sits in the basement clamped to the street side of our water meter.

Whatdayathink ‘Packers’, zit gonna work?

OhioPrepper July 29, 2013 at 9:04 pm

TTT,
I have several 30 gallon metal trashcans setup in a similar manner, except I don’t use any coffin locks, or anything else on the lid since its already tight fitting.
Also, lose the ground connection. The wire acts as an antenna and unless you have a good way to measure things, my do more harm than good. Faraday enclosures do not have to be grounded, and that is not just my opinion, but the facts from the physics of how they work.
In general your setup should work fine.

Sirius August 3, 2013 at 4:13 pm

From what I read in the article, I’d say don’t loose the ground connection completely. Have it available. The good doctor in his article stated that the faraday cage may become charged itself and having a ground source readily available would be perfect to discharge the cage before you touch it.

bakdrft July 29, 2013 at 7:45 pm

I do appreciate the wonderful post people put here, but I do have a question. If I have to store all my electronic items in here how can Iuse them? If I take them out to use how can I put them back in before a EMP is used? Sooo It goes to reason we need to live in a Farady world…or a Faraday car or a…………sigh

M.D. Creekmore July 29, 2013 at 8:58 pm

bakdrft,

An EMP is not a continuous event, it is a burst of energy that is released, the damage is done, and then it’s gone, unless it is caused by a solar storm which could last for several hours or even days.

OhioPrepper July 29, 2013 at 9:13 pm

MD,
As stated in the article, a solar storm is not likely to produce effects that will hurt small electronic items, unless they are connected to an external long wiring system, which could include the electrical grid, your landline telephone, your local cable TV provider, all of which contain long enough antennas to induce large voltages onto the system, and into connected devices.
The Carrington Event of 1859 cause problems with telegraph offices because the telegraph wires between the offices acted as a large antenna system, which collected the energy and delivered it to the devices connected to it. Things like spare unconnected batteries stored in those same offices would not have been affected.

OhioPrepper July 29, 2013 at 9:22 pm

bakdrft,
If vulnerable equipment is not in the protected enclosure during the event, then it could be subject to damage. The idea is to store currently unused or spare equipment in the protected environment. I am also one who thinks multiple small enclosures are better than one large enclosure, so that a failure doesn’t damage everything you own. I do the same with my long term food preps, opting to have #10 cans of things like wheat rather than 5 gallon buckets. If the contents of a 5 pound can spoil, it’s a lot less loss than the contents of a 35 pound pail. Likewise for the contents of a single, smaller protective enclosure.

charlie (NC) July 29, 2013 at 9:09 pm

The truth is that no one knows for sure what will work without knowing the exact characteristics of electromagnetic pulse and that is impossible to know in advance. I think a metal trash can is as good as anything. I have one lined with heavy cardboard with the seams taped to act as an insulator. However I expected that it would shield
radio waves so I put a portable radio inside it and put the lid on.
The radio continued to play so who knows. I guess the can was resonant to the frequency of radio station. I had the cardboard cut so that the galvanized metal top touched the galvanized metal can when the top was on.

I’m wondering about some sort of combination container. For example a non conductive box with a fine wire screen around it with the wire screen covered with a non conductor and all of that inside a solid metal container.

You just never know what an energy source will decide to do or where it will go. For example, my house was hit by lighting many years ago.
At the time of the strike there was a window A/C, a TV set and a refrigerator plugged in and running. They were not hurt but the lightning strike blew the main breakers out of the breaker box taking the box cover door off with them. Every light bulb in the wall circuit that the TV was plugged into was blown even though none of them were switched on and the TV was on but was not hurt. All of the outdoor flood lights and driveway lights were destroyed. I mean lights and wiring were destroyed but none of them were switched on. It’s clear from that the lightning didn’t follow the easiest path to ground.
It also didn’t hurt the water pump or the water heater or furnace. All of them were tied to the common house ground.

I know that lightning isn’t RF or an EMP but it is a huge energy source and I predict EMP will be just as unpredictable. The long and short of it is do the best you can. Build more than one type of faraday cage. Place them in different locations and split your gear between them. Then hope for the best.

OhioPrepper July 29, 2013 at 9:33 pm

Arthur,
As a EE I think that this article was spot on; although perhaps a little more complex in the description of the physics than it would have to be . Good job.

Arthur Bradley August 7, 2013 at 10:23 am

Thanks, I appreciate it! I’m an electrical engineer too.

Arthur

Chuck Findlay July 29, 2013 at 11:17 pm

The first thing is that I don’t see an EMP strike as a very likely event. But with that said I do apply a little protection to this very small possibility.

My faraday cage is an old white metal cabinet I tore out of a house I was updating. It looks to be made in the 1960s and is as strong as the day it was made. It’s just dated in it’s style. It resides in my basement and the electronic items in it don’t seem to care if it looks dated. And the price was right, it was free. In fact I got paid to remove it and haul it away.

And it’s easy to put things into and take them out of it.

bakdrft July 29, 2013 at 11:24 pm

I dont think you all got my point, You have explained what an EMP does and how long it lasts, but you, me and everyone here does NOT know when one will happen. THAT is my point WE dont know when one will happen. So keeping your electronics stored in a Faraday container does no good if you have the irrational fear that a EMP/Solar burst will happen. I must point out that even if your cell phone works cuz you protected it in your faraday box the cell towers/internet wont be working. So whew you have a cute little paperweight that can make a phone call to no one else. I want to think I can get around when TSHTF happens without the dependence of a cellular device,Who are you going to call? 911 we are knocked out as well. I dont store my fire engines in an encapsulated faraday fire dept.

gil July 30, 2013 at 3:49 pm

you could keep a laptop you dont use with alot of pdf files . sim cards, flashdrives, if it large enough a small tv,dvd combo , 2 way radios, ect…

charlie (NC) July 30, 2013 at 6:09 pm

What you keep in your Faraday cage always are the spare electronic parts for your car or truck, your spare ham radio, your extra laptop computer, etc. etc. Then you put your everyday items in the Faraday cage when you aren’t using them for a while. Otherwise you use them and don’t worry about it because you have your spares put away. It’s not that complicated.

The amount of stuff you keep stored away depends on your risk tolerance. Some folks don’t have insurance. Some folks have too much insurance. It’s the same thing. It’s just insurance in the form of electronic items.

Chuck Findlay July 29, 2013 at 11:32 pm

Hey MD that “Bad Idea” t-shirt add is very distracting.
I think you need more like it…

Millie in KY July 29, 2013 at 11:45 pm

Sooo….we hear about the event and hustle to put our electronics away? I guess I’m confused, if a small nuclear device is set off in the upper atmosphere with the intention of doing harm to our electronics, we probably would have no warning. We would keep our stuff in there all the time? That doesn’t make any sense to me at all….someone please explain why this is important, as someone said, if my stuff is put away, how do I use it? Thanks!

Seamus Finn July 30, 2013 at 12:05 pm

The whole point is to stuff up a few spare electronics in your cage. A CB radio, flashlights, AM/FM radio (just in case…), electronic tools of value, etc.

Not only comm equipment. A glucometer, for example, is almost vital to a diabetic person. And it could fry in an EMP. Better have a spare one stashed somewhere safe =P

You do not use your stuff. Your everyday gear will fry. That’s it, there’s nothing you can do about it. It’s your preps you need to store =)

Ben Price July 30, 2013 at 12:35 am

In a word, bogus, all of it. Neither the author nor anyone replying has any idea how a faraday cage really works. But if y’all want to put your electronics in trash cans and expect them to survive an emp, at least you will be one step ahead of the rest when they pop. A trash can will be a good place to leave them after they are fried.

A faraday cage must have a good earth ground. It should be constructed of perforated metal, preferably copper. It should have no open seams, and the contents need to be electrically isolated from the cage if they are to be protected.

The reason for the earth ground is that the cage IS NOT A SHIELD, it is a shunt. It will not deflect EMP energy, it has to drain the energy instantly from the surface of the cage before it builds up a charge and becomes electrically transparent. The perforations are necessary to break up eddy currents in the metal, otherwise it will induce a saturating field that will re-radiate into the cage.

But go ahead and use the garbage cans, the ammo cans, the aluminum foil packets, the coffee cans, etc. and see what happens.

From one with REAL experience building, testing, and using faraday cages for a living.

PWB July 30, 2013 at 5:57 pm

Ben,you may be right but your presentation leaves a lot to be desired. just sayin.

charlie (NC) July 30, 2013 at 6:13 pm

Ben, I don’t particularly like your attitude but I’ll reply anyway.
Lots of people know how a Faraday cage works. What we don’t know is the characteristics of the EMP event. Without that information we are guessing on what to protect against.

Macintosh July 30, 2013 at 6:25 pm

It’s good that you do such important work with things for a living because if you had to interact with people you would be out of a job.

Arthur Bradley August 7, 2013 at 10:27 am

I think that you’re confusing the characteristics of an EMP with that of lightning. The goal with lightning is indeed to shunt it away (thus the use of lightning rods). An EMP is a high frequency radiated event (not conducted like a bolt of lightning), so the goal is to simply shield the sensitive electronics from the high electromagnetic fields. I am not sure of your experience, but I say this as a NARTE certified EMC engineer who has worked in electromagnetics for 20 years.

As for garbage cans, they do a pretty good job as I show in my book.

Best wishes,

Arthur

kondejko September 5, 2013 at 4:43 am

can a dryer be used as a Faraday cage

Chuck Findlay July 30, 2013 at 12:43 am

I use my stuff as normal. But I work hard to have backups of almost everything. These things have to be stored someplace, why not the metal cabinet I got for free. Its convent as it has shelves in it and it is made from metal.

Like I said, I don’t worry about EMP, but it’s easy to put things in this cabinet. I don’t expect to have a serious auto accident, but that doesn’t mean I don’t buy coverage for it. I look at EMP the same way, I cover my bets.

charlotte morris August 2, 2013 at 11:57 pm

Agree, that is the way to look at it.

Rick July 30, 2013 at 10:58 am

I’ll take a chance with my old microwave I have. It’s tidier than lining a closet with tin foil, which looks like I’m doing something illegal, and it lets me avoid hauling the old clunker out to the curb. I only have a couple walkie-talkies, a transistor radio and a couple flashlights in it, with no batteries in them.

If it does happen, I figure it at least gives me a fighting chance, and if I do have a break-in, chances are that the burglars will overlook that antique. I did snip the cord in preparation to junk it, but managed to procrastinate tossing it. I’m glad I did now.

Seamus Finn July 30, 2013 at 12:06 pm

And that microwave of yours already is some kind of Faraday cage, by the way.

It was designed this way =P Not to let the… micro-waves out of the oven.

Onion July 30, 2013 at 7:31 pm

http://www.futurescience.com/emp.html – it echos, and expands upon, the advice of the OP, and it’s free.

No shield is 100% protective. Every electronic device will have a different failure threshold. The pulse strength will vary based on it’s height, your distance from it, and the magnitude of the blast. Cages attenuate the strength of the pulse the item within receives, they don’t fully negate it. The skin effect is fact, multiple thin shields, each insulted from each other, is far superior to a single thicker shield like a trash can. Conductor, insulator, conductor, insulator, etc, device. Read: electronic item(s) in a paper bag, wrapped in tinfoil, inside another paper bag, wrapped by tinfoil, inside another paper bag, wrapped in tinfoil. Improper grounds are worse than none at all. A copper wire to a grounding rod, or a water pipe, is not a proper ground for EMP.

Arthur Bradley August 7, 2013 at 10:29 am

You’re absolutely right about the multiple layer effects working better than a thick conductor. I didn’t have time to talk about that in this article, but it is discussed in a youtube video that I did. Check out disasterprepper videos (or my name) and you’ll find one on Faraday Cage testing.

Arthur

T.R. July 30, 2013 at 7:59 pm

I have a lead lined ammo box , that was originally used to transport radioactive pharmaceuticals in for small stuff .

Ben Price July 31, 2013 at 4:42 am

Yes, my delivery does leave something to be desired. My apologies to the pack. I get irritated having to repeat myself often regarding all the mis-information going on with phony/inadequate faraday cage specifications.

An EMP is an induced pulse of electromagnetic/electrostatic energy ranging from very low frequency (heave) to extremely high frequency (Compton effect). There are several components to the nuclear detonation type emp that have to be considered. Also, the altitude of the detonation is a factor in electrostatic/electromagnetic generation. The theory behind nuclear emp gets rather complicated to explain, so I would offer a rather simplified analogy.

Instead of thinking of a faraday cage like you would an umbrella in a rainstorm, think of it instead like a sponge you are standing under. If the storm is small and short, the sponge will absorb enough moisture that you don’t get soaked. But if the storm is heavy and/or long, the sponge will saturate, and you will end up as wet as if you had no sponge at all to protect you. Now imagine if the sponge had 4 pipes sticking out of the corners, stuck in the sponge so that they could drain the sponge before it saturates. Then you could stand under it during a heavy storm and still stay dry. However, under the worst storm conditions, even the pipes would not be enough, and you would end up soaking wet after all.

That is perhaps the best analogy I can come up with for how a faraday cage is supposed to work. The pipes are the same as the grounding rods. If the rods are not coupled to both the cage and earth ground well, then they will not shunt the energy sufficiently to protect what is inside. If the emp is big enough, it will overcome the abilities of the cage. I have never seen or heard of a faraday cage that will protect against ANY emp. But unless it is well grounded, it won’t provide any protection at all.

If you want to understand emp better, visit the site www. fas.org, or do a google search on nuclear emp. Also do search on “mitigating emp” and do a lot of reading.

I’ve had to harden communications sites, some of the most vulnerable equipment to emp, to survive direct lightning strikes. Lightning is freakishly difficult to protect against electrically. But it is not as bad as nuclear emp can be.

My apologies if I seem curt or irritated. It is because I have repeated this so many times I wonder if anyone is listening.

charlie (NC) July 31, 2013 at 8:43 am

Ben, finally a useful comment from you. Thanks and I mean that sincerely. This groups includes folks from all different
backgrounds, levels of experience and education so please don’t make the assumption that all or even most of us are too ignorant to understand you. As I told my doctor once. I understand the English language if you can speak it.

I don’t mean those comments to be harsh. I guess you can tell that you are not the only member of this group with a hopelessly abrasive tongue. Your analogy with the sponge and the pipes is the best word picture I’ve ever read/seen of an effective faraday cage.

Am I right in thinking that probably the very best protection for
an EMP is to bury your stuff under about 5 or 6 feet of soil?

Ben Price July 31, 2013 at 10:29 pm

Deeper would be better, but keep in mind depth is a bit subjective. What you really need is a good coupling to earth ground. That depends more on soil conductivity and things like ambient moisture, mineralization, as well as depth. Dissipating the energy over a broad area quickly is the objective. EMPs are neutralized quite well in the ocean.

I am a bit of a curmudgeon at times. Usually I don’t have such an abrasive tone on my responses. I guess the stress at work has been getting to me a bit lately. Again, my apologies.

william Kraft September 3, 2013 at 12:14 am

Just curious, if you need an earth ground how far away from your cage would you place it.

Thomas T. Tinker July 31, 2013 at 8:47 pm

Well Crappolla boys and girls, don’t you love the constructive interaction. Somebody with a plan kindly write it up with some art work attached. Hell everybody with a plan do a write up and we can all hope to find something that will protect our spare am radio and IPod!

Me….. I believe I’ll just attach a ‘defferent’ style of lid, a kind of seat really, and use mine as a standby crapper.

Tell be Packers….. what is the effect of a nice juicy EMP on brass cased ammunition and mylar bagged pasta?

Trish August 2, 2013 at 12:22 am

I’ve read so many articles, and Dr. Bradley’s books (very intelligent on the prepper front!), and there is a ton of information on the web and in books about EMP’s (both solar and nuclear) and it can get confusing.
Some say that anything that can be disrupted by a magnet can be wiped clean of all information, short circuited, etc. So flash drives, CD’s, DVD’s, computers, etc can all be wiped clean and also rendered unusable.
Having a backup of all of your information in a safe place….not on some distant server because it will definitely be wiped clean…..like a faraday cage would be the best route to use. IF you can afford it, buy a backup of all electronic equipment…..laptops, walkie talkies, emergency radio, ham radio, etc. Not sure about battery operated stuff like flashlights, especially ones with batteries in them, but they would probably be best kept in a faraday cage as well. I’ve got so much backed up on various types of discs and flash drives that I’ve lost track of all of the info and pictures and music I’ve got. But I do have a laptop that I don’t use except during storms, so I plan on putting it into a faraday cage of some design. A metal trash can would be best as it can be used for trash after the EMP is over. I’m going to put a rubber mat on the floor, plus the inside of the lid, and up the sides to add to the protection, as well as running a copper wire into the ground from the handles so the extra energy will be shunted off into the ground. At the moment, I live in the basement of an 1895 house that has a hand laid brick floor without mortar, so putting a copper wire into the floor would not be a hard thing to do.
If you can find the Apocalypse 101 shows that were on National Geographic, (look on the National Geographic site or YouTube) the guys actually made a faraday cage, and it seemed to work pretty well. They used a rubber floor mat on the bottom of the cage, and shunted the energy off into the ground from the cage with a copper wire and a metal pole of some sort.
I’m not a huge fan of surge protectors because my computer has been fried TWICE being plugged into them. So I’m not a big advocate of the surge protection devices. During a severe thunderstorm….my computer gets shut off and the surge protector unplugged from the wall. Earlier this year it was unplugged for almost a month for all of the severe storms rolling through here. Didn’t make much sense to plug it back in when I was just going to have to unplug it a day later.

PrepperNurse August 5, 2013 at 9:16 pm

this is my first visit to the site. I agree with many comments, but I believe we should all respect each other in a professional manner. For an EMP….which could have happened 2 weeks ago with the Earth that just dodged a large solar flare, I keep spare items in an old insulated Colman cooler from the 1960s….the metal outside and insulated inside. I read somewhere that this would do well for the box and you can find the cooler relatively cheep at garage sales and auction houses. Just need to clean it and if so desired, throw a coat of spray paint on it. A metal tool box will work as well but make sure you line it with Styrofoam to place your item(s) on. I do like the idea of grounding… will consult with my father who was a mechanical and electrical engineer before he retired.

Thank you all for stuff to think about.

mitten mom August 7, 2013 at 7:39 pm

Newbie here, so I apologize if this has been addressed before or if it is so basic that it is a “given”. Would galvanized sheet metal, the same type that is used for ductwork for HVAC, be appropriate? My husband is in the HVAC industry and that is something we have at our disposal. I realize that insulation of some type would be needed, along with the other specs that are required. I have searched for info on this but haven’t been able to come up with this answer. Thanks to all of you for making this site so worthwhile!!

Mitten Mom August 7, 2013 at 8:58 pm

Newbie here, so I apologize if this has been addressed before or if it is so basic that it is a “given”. Would galvanized sheet metal, the same type that is used for ductwork for HVAC be appropriate? My husband is in the HVAC industry and that is something we have at our disposal. I realize that insulation of some type would be needed, along with the other specs that are required. I have searched for info on this but haven’t been able to come up with the answer. Thanks to all of you for making this site so worthwhile.

terry August 14, 2013 at 4:37 pm

Hi
great info
would a Faraday cage help people that have electrosensitivity to be able to use computers ?
maybe put the computer in the cage or make the cage big enough for the ElectroSensitive person to get in so they can use a computer ?
any thoughts or ideas ??
thanks

David September 13, 2013 at 4:07 pm

Thank you for the instructions! Very informative. I was wondering if you could also show designs for some kind of Faraday hat? I think it would be helpful to a lot of readers (myself included).

A. Burton September 24, 2013 at 5:32 am

Okay so I understand the need for a Faraday cage and everything, but what is the point of having all of that stuff when it can’t really be used very long without a power source to recharge it? Let’s say a solar flare fries the electrical grid and you managed to save your laptop from the damage…You can only use it until the battery dies and then it is useless again. So unless you build a Faraday Cage to go around a generator or something that allows you to recharge it (and you don’t get killed from the attraction of everyone realizing you have a power source still) everything will eventually become useless. As for a radio who are you listening for over it without anyone having the ability to broadcast? I guess my point is… isn’t it pointless to save any of that without some way to power them again long term?

Mark October 12, 2013 at 11:43 pm

If I built my trash can Faraday cage, put my cell phone in there with the lid on tight, and it could still receive a text message, is it safe to say my cage is worthless against a powerful EMP?

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